Matte finish polyimide films and methods relating thereto

ABSTRACT

The present disclosure is directed to a base film having a chemically converted polyimide, a particulate polyimide matting agent and a low conductivity carbon black. The particulate polyimide matting agent is present in an amount from 1.6 to 9 weight percent of the base film.

This application is a continuation of application Ser. No. 15/453,114filed on Mar. 8, 2017, now U.S. Pat. No. 10,336,045, which claimspriority to application Ser. No. 13/625,167 filed on Sep. 24, 2012, nowU.S. Pat. No. 9,631,054, which claims priority to application Ser. No.12/842,174 filed on Jul. 23, 2010, now U.S. Pat. No. 8,574,720, whichclaims benefit of provisional Application Ser. No. 61/230,934, filed onAug. 3, 2009.

FIELD OF DISCLOSURE

The present disclosure relates generally to matte finish base films thatare useful in coverlay applications and have advantageous dielectric andoptical properties. More specifically, the matte finish base films ofthe present disclosure comprise a relatively low concentration ofpigment and particulate polyimide matting agent in a polyimide filmimidized by a chemical (as opposed to a thermal) conversion process.

BACKGROUND OF THE DISCLOSURE

Broadly speaking, coverlays are known as barrier films for protectingelectronic materials, e.g., for protecting flexible printed circuitboards, electronic components, leadframes of integrated circuit packagesand the like. A need exists however, for coverlays to be increasinglythin and low in cost, while not only having acceptable electricalproperties (e.g., dielectric strength), but also having acceptablestructural and optical properties to provide security against unwantedvisual inspection and tampering of the electronic components protectedby the coverlay.

SUMMARY

The present disclosure is directed to a base film having a chemicallyconverted polyimide, a particulate polyimide matting agent and a lowconductivity carbon black. The particulate polyimide matting agent ispresent in an amount from 1.6 to 9 weight percent of the base film.

DETAILED DESCRIPTION Definitions

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a method,process, article, or apparatus that comprises a list of elements is notnecessarily limited only to those elements but may include otherelements not expressly listed or inherent to such method, process,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

Also, use of the “a” or “an” are employed to describe elements andcomponents of the invention. This is done merely for convenience and togive a general sense of the invention. This description should be readto include one or at least one and the singular also includes the pluralunless it is obvious that it is meant otherwise.

“Dianhydride” as used herein is intended to include precursors orderivatives thereof, which may not technically be a dianhydride butwould nevertheless react with a diamine to form a polyamic acid whichcould in turn be converted into a polyimide.

“Diamine” as used herein is intended to include precursors orderivatives thereof, which may not technically be a diamine but wouldnevertheless react with a dianhydride to form a polyamic acid whichcould in turn be converted into a polyimide.

“Polyamic acid” as used herein is intended to include any polyimideprecursor material derived from a combination of dianhydride and diaminemonomers or functional equivalents thereof and capable of conversion toa polyimide via a chemical conversion process.

“Chemical conversion” or “chemically converted” as used herein denotesthe use of a catalyst (accelerator) or dehydrating agent (or both) toconvert the polyamic acid to polyimide and is intended to include apartially chemically converted polyimide which is then dried at elevatedtemperatures to a solids level greater than 98%.

When an amount, concentration, or other value or parameter is given aseither a range, preferred range or a list of upper preferable values andlower preferable values, this is to be understood as specificallydisclosing all ranges formed from any pair of any upper range limit orpreferred value and any lower range limit or preferred value, regardlessof whether ranges are separately disclosed. Where a range of numericalvalues is recited herein, unless otherwise stated, the range is intendedto include the endpoints thereof, and all integers and fractions withinthe range. It is not intended that the scope of the invention be limitedto the specific values recited when defining a range.

In describing certain polymers, it should be understood that sometimesapplicants are referring to the polymers by the monomers used to makethem or the amounts of the monomers used to make them. While such adescription may not include the specific nomenclature used to describethe final polymer or may not contain product-by-process terminology, anysuch reference to monomers and amounts should be interpreted to meanthat the polymer is made from those monomers, unless the contextindicates or implies otherwise.

The materials, methods, and examples herein are illustrative only and,except as specifically stated, are not intended to be limiting. Althoughmethods and materials similar or equivalent to those described hereincan be used in the practice or testing of the present invention,suitable methods and materials are described herein.

Base Film

The base film of the present disclosure comprises a filled polyimidematrix, where the polyimide is created by a chemical conversion process.One advantage of a chemically converted polyimide (over a thermallyconverted polyimide) is that the amount of matting agent necessary toachieve sufficient low gloss is at least 10, 20, 30, 40 or 50 percentless than if a thermal conversion process is used. Generally acceptedranges for 60 degree gloss values are:

<10 flat 10-70 matte, satin, semi-gloss (various terms are used) >70glossy.In some embodiments, the base film has a 60 degree gloss value betweenand optionally including any two of the following: 2, 3, 4, 5, 10, 15,20, 25, 30 and 35. In some embodiments, the base film has a 60 degreegloss value from 2 to 35. In some embodiments, the base film has a 60degree gloss value from 10 to 35. The 60 degree gloss value is measuredusing Micro-TRI-Gloss gloss meter. The lower loading of matting agent(made possible by the chemical conversion) is advantageous, because it:i. lowers overall cost; ii. simplifies the dispersion of matting agentinto the polyamic acid (or other polyimide precursor material); and iii.provides the resulting base film with better mechanical properties(e.g., less brittleness). Another unexpected advantage of using achemically converted polyimide is that the film is matte on both sides,even if cast onto a smooth surface. If both sides of the base film arematte, any additional layers may be applied to either side of the basefilm. In contradistinction, when similarly filled polyimide precursorfilms are solely thermally converted and cast on a smooth surface, thecast side tends to be glossy and the air side tends to be matte. In someembodiments, the base film has a 60 degree gloss value from 2 to 35 onboth sides.

Yet another advantage is base films comprising a chemically convertedpolyimide have higher dielectric strength compared to base filmcomprising a solely thermally converted polyimide. Typically, thedielectric strength decreases as the amount of matting agent increases.So while low 60 degree gloss value can be achieved (air side only) inthe solely thermal process, by increasing the amount of matting agent,the dielectric strength will decrease. In some embodiments, the basefilm dielectric strength is greater than 1400 V/mil (55 V/micron).

In a chemical conversion process, the polyamic acid solution is eitherimmersed in or mixed with conversion (imidization) chemicals. In oneembodiment, the conversion chemicals are tertiary amine catalysts(accelerators) and anhydride dehydrating materials. In one embodiment,the anhydride dehydrating material is acetic anhydride, which is oftenused in molar excess relative to the amount of amic acid (amide acid)groups in the polyamic acid, typically about 1.2 to 2.4 moles perequivalent of polyamic acid. In one embodiment, a comparable amount oftertiary amine catalyst is used.

Alternatives to acetic anhydride as the anhydride dehydrating materialinclude: i. other aliphatic anhydrides, such as, propionic, butyric,valeric, and mixtures thereof; ii. anhydrides of aromatic monocarboxylicacids; iii. Mixtures of aliphatic and aromatic anhydrides; iv.carbodimides; and v. aliphatic ketenes (ketenes may be regarded asanhydrides of carboxylic acids derived from drastic dehydration of theacids).

In one embodiment, the tertiary amine catalysts are pyridine andbeta-picoline and are typically used in amounts similar to the moles ofanhydride dehydrating material. Lower or higher amounts may be useddepending on the desired conversion rate and the catalyst used. Tertiaryamines having approximately the same activity as the pyridine, andbeta-picoline may also be used. These include alpha picoline;3,4-lutidine; 3,5-lutidine; 4-methyl pyridine; 4-isopropyl pyridine;N,N-dimethylbenzyl amine; isoquinoline; 4-benzyl pyridine,N,N-dimethyldodecyl amine, triethyl amine, and the like. A variety ofother catalysts for imidization are known in the art, such asimidazoles, and may be useful in accordance with the present disclosure.

The conversion chemicals can generally react at about room temperatureor above to convert polyamic acid to polyimide. In one embodiment, thechemical conversion reaction occurs at temperatures from 15° C. to 120°C. with the reaction being very rapid at the higher temperatures andrelatively slower at the lower temperatures.

In one embodiment, the chemically treated polyamic acid solution can becast or extruded onto a heated conversion surface or substrate. In oneembodiment, the chemically treated polyamic acid solution can be cast onto a belt or drum. The solvent can be evaporated from the solution, andthe polyamic acid can be partially chemically converted to polyimide.The resulting solution then takes the form of a polyamic acid-polyimidegel. Alternately, the polyamic acid solution can be extruded into a bathof conversion chemicals consisting of an anhydride component(dehydrating agent), a tertiary amine component (catalyst) or both withor without a diluting solvent. In either case, a gel film is formed andthe percent conversion of amic acid groups to imide groups in the gelfilm depends on contact time and temperature but is usually about 10 to75 percent complete. For curing to a solids level greater than 98%, thegel film typically must be dried at elevated temperature (from about200° C., up to about 550° C.), which will tend to drive the imidizationto completion. In some embodiments, the use of both a dehydrating agentand a catalyst is preferred for facilitating the formation of a gel filmand achieve desired conversion rates.

The gel film tends to be self-supporting in spite of its high solventcontent. Typically, the gel film is subsequently dried to remove thewater, residual solvent, and remaining conversion chemicals, and in theprocess the polyamic acid is essentially completely converted topolyimide (i.e., greater than 98% imidized). The drying can be conductedat relatively mild conditions without complete conversion of polyamicacid to polyimide at that time, or the drying and conversion can beconducted at the same time using higher temperatures. Because the gelhas so much liquid that must be removed during the drying and convertingsteps, the gel generally must be restrained during drying to avoidundesired shrinkage. In continuous production, the base film can be heldat the edges, such as in a tenter frame, using tenter clips or pins forrestraint. High temperatures can be used for short times to dry the basefilm and induce further imidization to convert the gel film to apolyimide base film in the same step. In one embodiment, the base filmis heated to a temperature of 200° C. to 550° C. Generally, less heatand time are required for thin films than for thicker films. During suchdrying and converting (from polyamic acid to polyimide), the base filmcan be restrained from undue shrinking and, in fact, may be stretched byas much as 150 percent of its initial dimension. In film manufacture,stretching can be in either the longitudinal direction or the transversedirection or both. If desired, restraint can also be adjusted to permitsome limited degree of shrinkage.

In one embodiment, the polyamic acids are made by dissolvingapproximately equimolar amounts of a dianhydride and a diamine in asolvent and agitating the resulting solution under controlledtemperature conditions until polymerization of the dianhydride and thediamine is completed. Typically, a slight excess of one of the monomers(usually diamine) is used to initially control the molecular weight andviscosity which can then be increased later via small additional amountsof the deficient monomer.

In some embodiments, the chemically converted polyimide is derived fromat least one aromatic dianhydride and at least one aromatic diamine. Insome embodiments, the chemically converted polyimide is present in anamount between and including any two of the following: 61, 65, 70, 75,80, 85, 90, 95 and 96 weight percent of the base film. In anotherembodiment, the chemically converted polyimide is derived from at least50 mole percent of an aromatic dianhydride, based upon a totaldianhydride content of the chemically converted polyimide, and at least50 mole percent of an aromatic diamine based upon a total diaminecontent of the chemically converted polyimide.

In one embodiment, the aromatic dianhydride is selected from the groupconsisting of:

-   -   pyromellitic dianhydride;    -   3,3′,4,4′-biphenyl tetracarboxylic dianhydride;    -   3,3′,4,4′-benzophenone tetracarboxylic dianhydride;    -   4,4′-oxydiphthalic anhydride;    -   3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride;    -   2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane;    -   bisphenol A dianhydride; and    -   mixtures and derivatives thereof.        In another embodiment, the aromatic dianhydride is selected from        the group consisting of:    -   2,3,6,7-naphthalene tetracarboxylic dianhydride;    -   1,2,5,6-naphthalene tetracarboxylic dianhydride;    -   2,2′,3,3′-biphenyl tetracarboxylic dianhydride;    -   2,2-bis(3,4-dicarboxyphenyl) propane dianhydride;    -   bis(3,4-dicarboxyphenyl) sulfone dianhydride;    -   3,4,9,10-perylene tetracarboxylic dianhydride;    -   1,1-bis(2,3-dicarboxyphenyl) ethane dianhydride;    -   1,1-bis(3,4-dicarboxyphenyl) ethane dianhydride;    -   bis(2,3-dicarboxyphenyl) methane dianhydride;    -   bis(3,4-dicarboxyphenyl) methane dianhydride;    -   oxydiphthalic dianhydride;    -   bis(3,4-dicarboxyphenyl) sulfone dianhydride;    -   mixtures and derivatives thereof.        Examples of aliphatic dianhydrides include:    -   cyclobutane dianhydride;    -   [1S*,5R*,6S*]-3-oxabicyclo[3.2.1]octane-2,4-dione-6-spiro-3-(tetrahydrofuran-2,5-dione);        mixtures thereof.

Examples of suitable diamines for use in the chemically convertedpolyimides of the present disclosure include aromatic diamines,aliphatic diamines and mixtures thereof. In one embodiment, the aromaticdiamine is selected from a group consisting of:

-   -   3,4′-oxydianiline;    -   1,3-bis-(4-aminophenoxy) benzene;    -   4,4′-oxydianiline;    -   1,4-diaminobenzene;    -   1,3-diaminobenzene;    -   2,2′-bis(trifluoromethyl) benzidene;    -   4,4′-diaminobiphenyl;    -   4,4′-diaminodiphenyl sulfide;    -   9,9′-bis(4-amino)fluorene;

mixtures and derivatives thereof.

In another embodiment, the aromatic diamine is selected from a groupconsisting of:

-   -   4,4′-diaminodiphenyl propane;    -   4,4′-diamino diphenyl methane;    -   benzidine;    -   3,3′-dichlorobenzidine;    -   3,3′-diamino diphenyl sulfone;    -   4,4′-diamino diphenyl sulfone;    -   1,5-diamino naphthalene;    -   4,4′-diamino diphenyl diethylsilane;    -   4,4′-diamino diphenysilane;    -   4,4′-diamino diphenyl ethyl phosphine oxide;    -   4,4′-diamino diphenyl N-methyl amine;    -   4,4′-diamino diphenyl N-phenyl amine;    -   1,4-diaminobenzene (p-phenylene diamine);    -   1,2-diaminobenzene;    -   Mixtures and derivatives thereof.        Examples of suitable aliphatic diamines include:    -   hexamethylene diamine,    -   dodecane diamine,    -   cyclohexane diamine;    -   and mixtures thereof.        In one embodiment, the chemically converted polyimide is derived        from        a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of:    -   pyromellitic dianhydride,    -   3,3′,4,4′-biphenyl tetracarboxylic dianhydride,    -   3,3′,4,4′-benzophenone tetracarboxylic dianhydride;    -   4,4′-oxydiphthalic anhydride,    -   3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,    -   2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane,    -   bisphenol A dianhydride, and mixtures thereof;        b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:    -   3,4′-oxydianiline,    -   1,3-bis-(4-aminophenoxy) benzene,    -   4,4′-oxydianiline,    -   1,4-diaminobenzene,    -   1,3-diaminobenzene,    -   2,2′-bis(trifluoromethyl) benzidene,    -   4,4′-diaminobiphenyl,    -   4,4′-diaminodiphenyl sulfide,    -   9,9′-bis(4-amino)fluorene and mixtures thereof.

In one embodiment, the chemically converted polyimides of the presentdisclosure are copolyimides derived from any of the above diamines anddianhydrides. In one embodiment, the copolyimide is derived from 15 to85 mole % of biphenyltetracarboxylic dianhydride, 15 to 85 mole %pyromellitic dianhydride, 30 to 100 mole % p-phenylenediamine andoptionally including 0 to 70 mole % of 4,4′-diaminodiphenyl ether and/or4,4′-diaminodiphenyl ether. Such copolyimides are further described inU.S. Pat. Nos. 4,778,872 and 5,166,308.

In one embodiment, the chemically converted polyimide dianhydridecomponent is pyromellitic dianhydride (“PMDA”) and the chemicallyconverted polyimide diamine component is a combination of4,4′-oxydianiline (“4,4 ODA”) and p-phenylenediamine (“PPD”). In oneembodiment the chemically converted polyimide dianhydride component ispyromellitic dianhydride (“PMDA”) and the chemically converted polyimidediamine component is a combination of 4,4′-oxydianiline (“4,4 ODA”) andp-phenylenediamine (“PPD”), where the ratio of ODA to PPD (ODA:PPD) isany of the following mole ratios: i. 20-80: 80-20; ii. 50-70:50-30; oriii. 55-65: 45-35. In one embodiment the chemically converted polyimidedianhydride component is PMDA, and the diamine component is a mole ratioof ODA to PPD (ODA:PPD) of about 60:40.

In one embodiment, the chemically converted polyimide dianhydridecomponent is 3,3′,4,4′-biphenyltetracarboxylic dianhydride (“BPDA”) andthe chemically converted polyimide diamine component is a combination of4,4′-oxydianiline (“4,4 ODA”) and p-phenylenediamine (“PPD”). In oneembodiment the chemically converted polyimide dianhydride component isBPDA and the chemically converted polyimide diamine component is acombination of 4,4 ODA and PPD, where the ratio of ODA to PPD (ODA:PPD)is any of the following mole ratios: i. 20-80: 80-20; ii. 50-70:50-30;or iii. 55-65: 45-35. In one embodiment the chemically convertedpolyimide dianhydride component is BPDA, and the diamine component is amole ratio of ODA to PPD (ODA:PPD) of about 60:40.

In one embodiment, the chemically converted polyimide is derived frompyromellitic dianhydride (“PMDA”) and 4,4′-oxydianiline (“4,4 ODA”). Inone embodiment, the chemically converted polyimide is derived from 100mole percent pyromellitic dianhydride and 100 mole percent4,4′-oxydianiline.

In one embodiment, the polyamic acid solvent must dissolve one or bothof the polymerizing reactants and in one embodiment, will dissolve thepolyamic acid polymerization product. The solvent should besubstantially unreactive with all of the polymerizing reactants and withthe polyamic acid polymerization product. In one embodiment the polyamicacid solvent is a liquid N,N-dialkylcarboxylamide, such as, a lowermolecular weight carboxylamide, particularly N,N-dimethylformamide andN,N-diethylacetamide. Other useful compounds of this class of solventsare N,N-diethylformamide and N,N-diethylacetamide. Other solvents whichmay be used are sulfolane, N-methyl-2-pyrrolidone, tetramethyl urea,dimethylsulfone, and the like. The solvents can be used alone or incombinations with one another. The amount of solvent used preferablyranges from 75 to 90 weight % of the polyamic acid.

The polyamic acid solutions are generally made by dissolving the diaminein a dry solvent and slowly adding the dianhydride under conditions ofagitation and controlled temperature in an inert atmosphere. In someembodiments, the base film has a thickness from 8 to 152 microns. Insome embodiments, the base film has a thickness from 8 to 127 microns.In yet another embodiment, the base film has a thickness from 10 to 40microns. The thickness of the base film can be tailored to the specificapplication.

In some embodiments, the base film is intended to be used as a coverlay.In such embodiments, it is desirable to hide the conductor traces in theflex circuits from view. The desired optical density (opacity) of thebase film (e.g., to hide the conductor traces in the flex circuits fromview) is greater than or equal to 2. An optical density of 2 is intendedto mean 1×10⁻² or 1% of light is transmitted through the base film.

Pigment

Virtually any pigment (or combination of pigments) can be used in theperformance of the present invention. In some embodiments, usefulpigments include but are not limited to the following: Barium LemonYellow, Cadmium Yellow Lemon, Cadmium Yellow Lemon, Cadmium YellowLight, Cadmium Yellow Middle, Cadmium Yellow Orange, Scarlet Lake,Cadmium Red, Cadmium Vermilion, Alizarin Crimson, Permanent Magenta, VanDyke brown, Raw Umber Greenish, or Burnt Umber. In some embodiments,useful black pigments include: cobalt oxide, Fe—Mn—Bi black, Fe—Mn oxidespinel black, (Fe,Mn)₂O₃ black, copper chromite black spinel, lampblack,bone black, bone ash, bone char, hematite, black iron oxide, micaceousiron oxide, black complex inorganic color pigments (CICP), CuCr₂O₄black, (Ni,Mn,Co)(Cr, Fe)₂O₄ black, Aniline black, Perylene black,Anthraquinone black, Chromium Green-Black Hematite, Chrome Iron Oxide,Pigment Green 17, Pigment Black 26, Pigment Black 27, Pigment Black 28,Pigment Brown 29, Pigment Black 30, Pigment Black 32, Pigment Black 33or mixtures thereof.

In some embodiments, a low conductivity carbon black is used. The amountof low conductivity carbon black and the thickness of the base film willgenerally impact the optical density. If the low conductivity carbonblack loading level is unduly high, the base film will be conductiveeven when a low conductivity carbon black is used. If too low, the basefilm may not achieve the desired optical density and color. The lowconductivity carbon black, for the purpose of this disclosure, is usedto impart the black color to the base film as well as to achieve thedesired optical density of a base film having a thickness between andoptionally including any two of the following: 8, 10, 15, 20, 25, 30,35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140 and 152 microns.In some embodiments, the base film has a thickness from 8 to 152microns. In some embodiments, the base film has a thickness from 8 to127 microns. In yet another embodiment, the base film has a thicknessfrom 10 to 40 microns.

Low conductivity carbon black is intended to mean, channel type black orfurnace black. In some embodiments, a bone black may be used to impartthe black color. In one embodiment, the low conductivity carbon black ispresent in amount between and optionally including any two of thefollowing: 2, 3, 4, 5, 6, 7, 8 and 9 weight percent of the base film. Insome embodiments, the optical density (opacity) desirable (e.g., to hidethe conductor traces in the flex circuits from view) is greater than orequal to 2. An optical density of 2 is intended to mean 1×10⁻² or 1% oflight is transmitted through the base film.

In some embodiments, the low conductivity carbon black is a surfaceoxidized carbon black. One method for assessing the extent of surfaceoxidation (of the carbon black) is to measure the carbon black'svolatile content. The volatile content can be measured by calculatingweight loss when calcined at 950° C. for 7 minutes. Generally speaking,a highly surface oxidized carbon black (high volatile content) can bereadily dispersed into a polyamic acid solution (polyimide precursor),which in turn can be imidized into a (well dispersed) filled polyimidebase polymer of the present disclosure. It is thought that if the carbonblack particles (aggregates) are not in contact with each other, thenelectron tunneling, electron hopping or other electron flow mechanismare generally suppressed, resulting in lower electrical conductivity. Insome embodiments, the low conductivity carbon black has a volatilecontent greater than or equal to 1%. In some embodiments, the lowconductivity carbon black has a volatile content greater than or equalto 5, 9, or 13%. In some embodiments, furnace black may be surfacetreated to increase the volatile content.

A uniform dispersion of isolated, individual particles (aggregates) notonly decreases the electrical conductivity, but additionally tends toproduce uniform color intensity. In some embodiments, the lowconductivity carbon black is milled. In some embodiments, the meanparticle size of the low conductivity carbon black is between (andoptionally including) any two of the following sizes: 0.2, 0.3, 0.4,0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 microns. The thickness of the base filmcan be tailored to the specific application.

In some embodiments, a mixture of dye and low conductivity carbon blackmay be used. In such embodiments, the base film additionally comprises adye present in an amount from 0.1 to 10 weight percent. In someembodiments, the dye is present between and including any two of thefollowing: 0.1, 1, 5, and 10 weight percent. Examples of useful dyesare, but not limited to, nigrosin black, monoazo chromium complex black,or mixtures thereof.

Matting Agent

Polymeric materials typically have inherent surface gloss. To controlgloss (and thereby produce matte surface characteristics) variousadditive approaches are possible to achieve dull and low gloss surfacecharacteristics. Broadly speaking, the additive approaches are all basedupon the same fundamental physics—to create a modified surface which is(on a micro-scale) coarse and irregular shaped and therefore allows lesslight to be reflected back to the distant (e.g., greater than 50centimeters) observer. When multiple rays of light hit a glossy surface,most of the light is reflected with similar angle and therefore arelatively high level of light reflectance can be observed. When thesame source of light hits a matte (ie. irregular) surface, the light isscattered in many different directions and also a much higher fractionis absorbed. Hence on rough surfaces, light tends to be diffuselyscattered in all directions, and the image forming qualities are largelydiminished (reflected objects no longer appear brilliant, but blurred).

Gloss meters used to characterize a specific surface for gloss level arebased on this same principle. Typically, a light source hits a surfaceat a fixed angle and after reflection the amount of reflected light isread by a photo cell. Reflection can be read at multiple angles. Maximumgloss performance for a perfectly glossy surface tends to demonstrate100% reflection, whereas a fully dull surface tends to demonstrate 0%reflection.

The amount of matting agent, median particle size and density must besufficient to produce the desired 60 degree gloss value. In someembodiments, the base film 60 degree gloss value is between andoptionally including any two of the following: 2, 5, 10, 15, 20, 25, 30and 35. In some embodiments, the base film 60 degree gloss value is from10 to 35. In some embodiments, the base film has a 60 degree gloss valuefrom 2 to 35 on both sides.

One matting agent that can be useful in polyimide applications (canwithstand the temperature processing of a chemically converted polyimide(processing temperatures of from about 250° C. to about 550° C.) arepolyimide particles. In some embodiments, the base film comprises aparticulate polyimide matting agent. In some embodiments, theparticulate polyimide matting agent is present in an amount between andoptionally including any two of the following: 1.6, 2, 3, 4, 5, 6, 7, 8,9 and 20 weight percent of base film. In some embodiments, when theamount of particulate polyimide matting agent is below 1.6 weightpercent of base film, the desired 60 degree gloss value is not achievedeven when the particulate polyimide matting agent median particle sizeand density are in the desired ranges.

In some embodiments, the particulate polyimide matting agent has amedian particle size between and optionally including any two of thefollowing: 1.3, 2, 3, 4, 5, 6, 7, 8, 9 and 10 microns. The particulatepolyimide matting agent should have a median particle size of less than(or equal to) about 10 microns and greater than (or equal to) about 1.3microns. If the median particle size of the particulate polyimidematting agent is greater than 10 microns, mechanical properties of thebase film may be negatively impacted. In some embodiments, when themedian particle size is below 1.3 microns, the desired 60 degree glossvalue is not achieved even when the amount of particulate polyimidematting agent and density are in the desired ranges.

In some embodiments, the particulate polyimide matting agent has adensity between and optionally including any two of the following: 1.3,1.4 and 1.5 g/cc. In one embodiment, a particulate polyimide mattingagent present in an amount from 1.6 to 20 weight percent of the basefilm and having a density from 1.3 to 1.5 g/cc.

In a preferred embodiment, the refractive index of the matting agentshould closely match the refractive index of the chemically convertedpolyimide. When the refractive indexes are close, there is less lightscattering at the chemically converted polyimide and matting agentinterface, resulting in lower haze and deeper, darker, more saturatedcolor from the low conductivity carbon black.

In some embodiments, the particulate polyimide matting agent has arefractive index from 1.65 to 1.85. In some embodiments, the particulatepolyimide matting agent has a refractive index between and including anytwo of the following: 1.65, 1.70, 1.75, 1.80 and 1.85. In someembodiments, the particulate polyimide matting agent has a refractiveindex from 1.65 to 1.85 and a median particle size from 1.3 to 10microns. In some embodiments, the particulate polyimide matting agenthas a refractive index between and including any two of the following:1.65, 1.70, 1.75, 1.80 and 1.85 and a median particle size between andincluding any two of the following: 1.3, 2, 3, 4, 5, 6, 7, 8, 9 and 10microns.

In some embodiments, the particulate polyimide matting agent and thechemically converted polyimide have a refractive index within andincluding 0.1 unit of each other. In some embodiments, the particulatepolyimide matting agent and the chemically converted polyimide have arefractive index within and including 0.1 unit of each other and amedian particle size from 1.3 to 10 microns. In some embodiments, theparticulate polyimide matting agent and the chemically convertedpolyimide have a refractive index within and including 0.1 unit of eachother and a median particle size between and including any two of thefollowing: 1.3, 2, 3, 4, 5, 6, 7, 8, 9 and 10 microns.

In some embodiments, the particulate polyimide matting agent is derivedfrom at least 50 mole percent of an aromatic dianhydride at least 50mole percent of an aromatic diamine. In some embodiments, theparticulate polyimide matting agent is derived from at least 50 molepercent of an aromatic dianhydride selected from the group consistingof:

pyromellitic dianhydride, 3,3′,4,4′-biphenyl tetracarboxylicdianhydride, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride;4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone tetracarboxylicdianhydride, 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol Adianhydride, and mixtures thereof; and at least 50 mole percent of anaromatic diamine selected from the group consisting of:3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,1,4-diaminobenzene, 1,3-diaminobenzene, 2,2′-bis(trifluoromethyl)benzidene, 4,4′-diaminobiphenyl, 4,4′-diaminodiphenyl sulfide,9,9′-bis(4-amino)fluorene and mixtures thereof.

The base film can be prepared by any method well known in the art formaking a chemically converted, filled polyimide layer. In one suchembodiment, a slurry comprising a low conductivity carbon black isprepared and a particulate polyimide matting agent slurry is prepared.The slurries may or may not be milled using a ball mill to reach thedesired particle size. The slurries may or may not be filtered to removeany residual large particles. A polyamic acid solution can be made bymethods well known in the art. The polyamic acid solution may or may notbe filtered. In some embodiments, the solution is mixed in a high shearmixer with the low conductivity carbon black slurry and the particulatepolyimide matting agent slurry. When a polyamic acid solution is madewith a slight excess of diamine, additional dianhydride solution may ormay not be added to increase the viscosity of the mixture to the desiredlevel for film casting. The amount of the polyamic acid solution, lowconductivity carbon black slurry, and particulate polyimide mattingagent slurry can be adjusted to achieve the desired loading levels inthe cured base film. In some embodiments, the mixture is cooled below 0°C. and mixed with conversion chemicals prior to casting onto a heatedrotating drum or belt in order to produce a partially imidized gel film.The gel film may be stripped from the drum or belt, placed on a tenterframe, and cured in an oven, using convective and radiant heat to removesolvent and complete the imidization to greater than 98% solids level.

Adhesive

In some embodiments, the base film is a multilayer film comprising thebase film of the present disclosure and an adhesive layer. The base filmof the present disclosure can comprise an adhesive layer for maintainingthe base film in place, once applied. In some embodiments, themultilayer film is a coverlay film.

In one embodiment, the adhesive consists of an epoxy resin and hardener,and, optionally, further contains additional components, such as, anelastomer, curing accelerator (catalyst), hardener, filler and flameretardant.

In some embodiments, the adhesive is an epoxy resin. In someembodiments, the epoxy resin is selected from the group consisting of:

-   -   Bisphenol F type epoxy resin,    -   Bisphenol S type epoxy resin,    -   Phenol novolac type epoxy resin,    -   Biphenyl type epoxy resin,    -   Biphenyl aralkyl type epoxy resin,    -   Aralkyl type epoxy resin,    -   Dicyclopetadiene type epoxy resin,    -   Multifunctional type epoxy resin,    -   Naphthalene type epoxy resin,    -   Rubber modified epoxy resin, and    -   mixtures thereof.

In another embodiment, the adhesive is an epoxy resin selected from thegroup consisting of bisphenol A type epoxy resin, cresol novolac typeepoxy resin, phosphorus containing epoxy resin, and mixtures thereof. Insome embodiments, the adhesive is a mixture of two or more epoxy resins.In some embodiments, the adhesive is a mixture of the same epoxy resinhaving different molecular weights.

In some embodiments, the epoxy adhesive contains a hardener. In oneembodiment, the hardener is a phenolic compound. In some embodiments,the phenolic compound is selected from the group consisting of: Novolactype phenol resin, Aralkyl type phenol resin, Biphenyl aralkyl typephenol resin, Multifunctional type phenol resin, Nitrogen containingphenol resin, Dicyclopetadiene type phenol resin, Phosphorus containingphenol resin, and Triazine containing phenol novolac resin.

In another embodiment, the hardener is an aromatic diamine compound. Insome embodiments, the aromatic diamine compound is a diaminobiphenylcompound. In some embodiments, the diaminobiphenyl compound is4,4′-diaminobiphenyl or 4,4′-diamino-2,2′-dimethylbiphenyl. In someembodiments, the aromatic diamine compound is a diaminodiphenylalkanecompound. In some embodiments, the diaminodiphenylalkane compound is4,4′-diaminodiphenylmethane or 4,4′-diaminodiphenylethane. In someembodiments, the aromatic diamine compound is a diaminodiphenyl ethercompound. In some embodiments, the diaminodiphenyl ether compounds is4,4′-diaminodiphenylether or di(4-amino-3-ethylphenyl)ether. In someembodiments, the aromatic diamine compound is a diaminodiphenylthioether compound. In some embodiments, the diaminodiphenyl thioethercompound is 4,4′-diaminodiphenyl thioether ordi(4-amino-3-propylphenyl)thioether. In some embodiments, the aromaticdiamine compound is a diaminodiphenyl sulfone compound. In someembodiments, the diaminodiphenyl sulfone compound is4,4′-diaminodiphenyl sulfone or di(4-amino-3-isopropylphenyl)sulfone. Insome embodiments, the aromatic diamine compound is phenylenediamine. Inone embodiment, the hardener is an amine compound. In some embodiments,the amine compound is a guanidine. In some embodiments, the guanidine isdicyandiamide (DICY). In another embodiment, the amine compound is analiphatic diamine. In some embodiments, the aliphatic diamine isethylenediamine or diethylenediamine.

In some embodiments, the epoxy adhesive contains a catalyst. In someembodiments, the catalyst is selected from the group consisting ofimidazole type, triazine type, 2-ethyl-4-methyl-imidazole, triazinecontaining phenol novolac type and mixtures thereof.

In some embodiments, the epoxy adhesive contains a elastomer tougheningagent. In some embodiments, the elastic toughening agent is selectedfrom the croup consisting of ethylene-acryl rubber,acrylonitrile-butadiene rubber, carboxy terminatedacrylonitrile-butadiene rubber and mixtures thereof.

In some embodiments, the epoxy adhesive contains a flame retardant. Insome embodiments, the flame retardant is selected from the groupconsisting of aluminum trihydroxide, melamine polyphosphate, condensedpolyphosphate ester, other phosphorus containing flame retardants andmixtures thereof.

In some embodiments, the adhesive layer is selected from the groupconsisting of: polyimide, butyral phenolic, polysiloxane,polyimidesiloxane, fluorinated ethylene propylene copolymers,perfluoroalkoxy copolymers, ethylene vinyl acetate copolymers, ethylenevinyl acetate glycidyl acrylate terpolymer, ethylene vinyl acetateglycidyl methacrylate terpolymer, ethylene alkyl acrylate copolymerswith adhesion promotor, ethylene alkyl methacrylate copolymers withadhesion promotor, ethylene glycidyl acrylate, ethylene glycidylmethacrylate, ethylene alkyl acrylate glycidyl acrylate terpolymer,ethylene alkyl methacrylate glycidyl acrylate terpolymer, ethylene alkylacrylate maleic anhydride terpolymers,

ethylene alkyl methacrylate maleic anhydride terpolymers, ethylene alkylacrylate glycidyl methacrylate terpolymers, ethylene alkyl methacrylateglycidyl methacrylate terpolymers, alkyl acrylate acrylonitrile acrylicacid terpolymers, alkyl acrylate acrylonitrile methacrylic acidterpolymers, ethylene acrylic acid copolymer including salts thereof,ethylene methacrylic acid copolymer including salts thereof, alkylacrylate acrylonitrile glycidyl methacrylate terpolymers, alkylmethacrylate acrylonitrile glycidyl methacrylate terpolymers, alkylacrylate acrylonitrile glycidyl acrylate terpolymers, alkyl methacrylateacrylonitrile glycidyl acrylate terpolymers, polyvinyl butyral, ethylenealkyl acrylate methacrylic acid terpolymers and salts thereof, ethylenealkyl methacrylate methacrylic acid terpolymers and salts thereof,ethylene alkyl acrylate acrylic acid terpolymers and salts thereof,ethylene alkyl methacrylate acrylic acid terpolymers and salts thereof,ethylene ethyl hydrogen maleate, ethylene alkyl acrylate ethyl hydrogenmaleate, ethylene alkyl methacrylate ethyl hydrogen maleate and mixturesthereof.

The adhesive can be applied to the base film by lamination or coating.Coating methods include, but are not limited to, spray coating, powdercoating, extrusion/slot die, gravure, offset gravure, roll coating, anddip/immersion.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide, and    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film; and        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film and having a        density from 1.3 to 1.5 g/cc.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent an aromatic dianhydride, based upon        a total dianhydride content of the chemically converted        polyimide, and    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc and having a median particle size from 1.3        to 10 microns.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride, based        upon a total dianhydride content of the chemically converted        polyimide, and    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns and having refractive index from 1.65 to 1.85.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride, based        upon a total dianhydride content of the chemically converted        polyimide, and    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns, having refractive index from 1.65 to 1.85; and        wherein the base film has a 60 degree gloss value from 2 to 35        on both sides.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride, based        upon a total dianhydride content of the chemically converted        polyimide, and    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film and having a        density from 1.3 to 1.5 g/cc, having a median particle size from        1.3 to 10 microns and wherein the particulate polyimide matting        agent and the chemically converted polyimide have a refractive        index within and including 0.1 unit of each other.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride, based        upon a total dianhydride content of the chemically converted        polyimide, and    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film and having a        density from 1.3 to 1.5 g/cc, having a median particle size from        1.3 to 10 microns, the particulate polyimide matting agent and        the chemically converted polyimide have a refractive index        within and including 0.1 unit of each other and wherein the base        film has a 60 degree gloss value from 2 to 35 on both sides.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride, based        upon a total dianhydride content of the chemically converted        polyimide, and    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc and wherein the particulate polyimide        matting agent is derived from at least 50 mole percent of an        aromatic dianhydride selected from the group consisting of:        pyromellitic dianhydride, 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride;        4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone        tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)        hexafluoropropane, bisphenol A dianhydride, and mixtures        thereof; and at least 50 mole percent of an aromatic diamine        selected from the group consisting of: 3,4′-oxydianiline,        1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,        1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride, based        upon a total dianhydride content of the chemically converted        polyimide, and    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns and wherein the particulate polyimide matting agent        is derived from at least 50 mole percent of an aromatic        dianhydride selected from the group consisting of: pyromellitic        dianhydride, 3,3′,4,4′-biphenyl tetracarboxylic dianhydride,        3,3′,4,4′-benzophenone tetracarboxylic dianhydride;        4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone        tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)        hexafluoropropane, bisphenol A dianhydride, and mixtures        thereof; and at least 50 mole percent of an aromatic diamine        selected from the group consisting of: 3,4′-oxydianiline,        1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,        1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride, based        upon a total dianhydride content of the chemically converted        polyimide, and    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns, having refractive index from 1.65 to 1.85 and        wherein the particulate polyimide matting agent is derived from        at least 50 mole percent of an aromatic dianhydride selected        from the group consisting of: pyromellitic dianhydride,        3,3′,4,4′-biphenyl tetracarboxylic dianhydride,        3,3′,4,4′-benzophenone tetracarboxylic dianhydride;        4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone        tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)        hexafluoropropane, bisphenol A dianhydride, and mixtures        thereof; and at least 50 mole percent of an aromatic diamine        selected from the group consisting of: 3,4′-oxydianiline,        1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,        1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride, based        upon a total dianhydride content of the chemically converted        polyimide, and    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns, having refractive index from 1.65 to 1.85, wherein        the particulate polyimide matting agent is derived from at least        50 mole percent of an aromatic dianhydride selected from the        group consisting of: pyromellitic dianhydride,        3,3′,4,4′-biphenyl tetracarboxylic dianhydride,        3,3′,4,4′-benzophenone tetracarboxylic dianhydride;        4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone        tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)        hexafluoropropane, bisphenol A dianhydride, and mixtures        thereof; and at least 50 mole percent of an aromatic diamine        selected from the group consisting of: 3,4′-oxydianiline,        1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,        1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof and wherein the base film has a 60 degree gloss        value from 2 to 35 on both sides.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride, based        upon a total dianhydride content of the chemically converted        polyimide, and    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns, wherein the particulate polyimide matting agent is        derived from at least 50 mole percent of an aromatic dianhydride        selected from the group consisting of: pyromellitic dianhydride,        3,3′,4,4′-biphenyl tetracarboxylic dianhydride,        3,3′,4,4′-benzophenone tetracarboxylic dianhydride;        4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone        tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)        hexafluoropropane, bisphenol A dianhydride, and mixtures        thereof; and at least 50 mole percent of an aromatic diamine        selected from the group consisting of: 3,4′-oxydianiline,        1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,        1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof; and wherein the particulate polyimide matting        agent and the chemically converted polyimide have a refractive        index within and including 0.1 unit of each other.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride, based        upon a total dianhydride content of the chemically converted        polyimide, and    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns, wherein the particulate polyimide matting agent is        derived from at least 50 mole percent of an aromatic dianhydride        selected from the group consisting of: pyromellitic dianhydride,        3,3′,4,4′-biphenyl tetracarboxylic dianhydride,        3,3′,4,4′-benzophenone tetracarboxylic dianhydride;        4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone        tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)        hexafluoropropane, bisphenol A dianhydride, and mixtures        thereof; and at least 50 mole percent of an aromatic diamine        selected from the group consisting of: 3,4′-oxydianiline,        1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,        1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof; wherein the particulate polyimide matting        agent and the chemically converted polyimide have a refractive        index within and including 0.1 unit of each other and wherein        the base film has a 60 degree gloss value from 2 to 35 on both        sides.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of: pyromellitic dianhydride, 3,3′,4,4′-biphenyl        tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone        tetracarboxylic dianhydride; 4,4′-oxydiphthalic anhydride,        3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,        2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A        dianhydride, and mixtures thereof;    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:        3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene,        4,4′-oxydianiline, 1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film; and        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film and having a        density from 1.3 to 1.5 g/cc.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of: pyromellitic dianhydride, 3,3′,4,4′-biphenyl        tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone        tetracarboxylic dianhydride; 4,4′-oxydiphthalic anhydride,        3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,        2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A        dianhydride, and mixtures thereof;    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:        3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene,        4,4′-oxydianiline, 1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film and having a        density from 1.3 to 1.5 g/cc and having a median particle size        from 1.3 to 10 microns.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of: pyromellitic dianhydride, 3,3′,4,4′-biphenyl        tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone        tetracarboxylic dianhydride; 4,4′-oxydiphthalic anhydride,        3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,        2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A        dianhydride, and mixtures thereof;    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:        3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene,        4,4′-oxydianiline, 1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns and having refractive index from 1.65 to 1.85.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of: pyromellitic dianhydride, 3,3′,4,4′-biphenyl        tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone        tetracarboxylic dianhydride; 4,4′-oxydiphthalic anhydride,        3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,        2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A        dianhydride, and mixtures thereof;    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:        3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene,        4,4′-oxydianiline, 1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns, having refractive index from 1.65 to 1.85 and        wherein the base film has a 60 degree gloss value from 2 to 35        on both sides.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of: pyromellitic dianhydride, 3,3′,4,4′-biphenyl        tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone        tetracarboxylic dianhydride; 4,4′-oxydiphthalic anhydride,        3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,        2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A        dianhydride, and mixtures thereof;    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:        3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene,        4,4′-oxydianiline, 1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns and wherein the particulate polyimide matting agent        and the chemically converted polyimide have a refractive index        within and including 0.1 unit of each other.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of: pyromellitic dianhydride, 3,3′,4,4′-biphenyl        tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone        tetracarboxylic dianhydride; 4,4′-oxydiphthalic anhydride,        3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,        2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A        dianhydride, and mixtures thereof;    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:        3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene,        4,4′-oxydianiline, 1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns, wherein the particulate polyimide matting agent and        the chemically converted polyimide have a refractive index        within and including 0.1 unit of each other and wherein the base        film has a 60 degree gloss value from 2 to 35 on both sides.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of: pyromellitic dianhydride, 3,3′,4,4′-biphenyl        tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone        tetracarboxylic dianhydride; 4,4′-oxydiphthalic anhydride,        3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,        2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A        dianhydride, and mixtures thereof;    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:        3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene,        4,4′-oxydianiline, 1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, and wherein the particulate polyimide        matting agent is derived from at least 50 mole percent of an        aromatic dianhydride selected from the group consisting of:        pyromellitic dianhydride, 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride;        4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone        tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)        hexafluoropropane, bisphenol A dianhydride, and mixtures        thereof; and at least 50 mole percent of an aromatic diamine        selected from the group consisting of: 3,4′-oxydianiline,        1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,        1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of: pyromellitic dianhydride, 3,3′,4,4′-biphenyl        tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone        tetracarboxylic dianhydride; 4,4′-oxydiphthalic anhydride,        3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,        2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A        dianhydride, and mixtures thereof;    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:        3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene,        4,4′-oxydianiline, 1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns, and wherein the particulate polyimide matting agent        is derived from at least 50 mole percent of an aromatic        dianhydride selected from the group consisting of: pyromellitic        dianhydride, 3,3′,4,4′-biphenyl tetracarboxylic dianhydride,        3,3′,4,4′-benzophenone tetracarboxylic dianhydride;        4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone        tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)        hexafluoropropane, bisphenol A dianhydride, and mixtures        thereof; and at least 50 mole percent of an aromatic diamine        selected from the group consisting of: 3,4′-oxydianiline,        1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,        1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of: pyromellitic dianhydride, 3,3′,4,4′-biphenyl        tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone        tetracarboxylic dianhydride; 4,4′-oxydiphthalic anhydride,        3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,        2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A        dianhydride, and mixtures thereof;    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:        3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene,        4,4′-oxydianiline, 1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns, having a refractive index from 1.65 to 1.85 and        wherein the particulate polyimide matting agent is derived from        at least 50 mole percent of an aromatic dianhydride selected        from the group consisting of: pyromellitic dianhydride,        3,3′,4,4′-biphenyl tetracarboxylic dianhydride,        3,3′,4,4′-benzophenone tetracarboxylic dianhydride;        4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone        tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)        hexafluoropropane, bisphenol A dianhydride, and mixtures        thereof; and at least 50 mole percent of an aromatic diamine        selected from the group consisting of: 3,4′-oxydianiline,        1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,        1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of: pyromellitic dianhydride, 3,3′,4,4′-biphenyl        tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone        tetracarboxylic dianhydride; 4,4′-oxydiphthalic anhydride,        3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,        2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A        dianhydride, and mixtures thereof;    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:        3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene,        4,4′-oxydianiline, 1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns, having a refractive index from 1.65 to 1.85 and        wherein the particulate polyimide matting agent is derived from        at least 50 mole percent of an aromatic dianhydride selected        from the group consisting of: pyromellitic dianhydride,        3,3′,4,4′-biphenyl tetracarboxylic dianhydride,        3,3′,4,4′-benzophenone tetracarboxylic dianhydride;        4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone        tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)        hexafluoropropane, bisphenol A dianhydride, and mixtures        thereof; and at least 50 mole percent of an aromatic diamine        selected from the group consisting of: 3,4′-oxydianiline,        1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,        1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof, and wherein the base film has a 60 degree        gloss value from 2 to 35 on both sides.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of: pyromellitic dianhydride, 3,3′,4,4′-biphenyl        tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone        tetracarboxylic dianhydride; 4,4′-oxydiphthalic anhydride,        3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,        2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A        dianhydride, and mixtures thereof;    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:        3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene,        4,4′-oxydianiline, 1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns, wherein the particulate polyimide matting agent is        derived from at least 50 mole percent of an aromatic dianhydride        selected from the group consisting of: pyromellitic dianhydride,        3,3′,4,4′-biphenyl tetracarboxylic dianhydride,        3,3′,4,4′-benzophenone tetracarboxylic dianhydride;        4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone        tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)        hexafluoropropane, bisphenol A dianhydride, and mixtures        thereof; and at least 50 mole percent of an aromatic diamine        selected from the group consisting of: 3,4′-oxydianiline,        1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,        1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof; and wherein the particulate polyimide matting        agent and the chemically converted polyimide have a refractive        index within and including 0.1 unit of each other.

In some embodiments, the base film comprises:

A. a chemically converted polyimide present in an amount from 61 to 96weight percent of the base film, the chemically converted polyimidebeing derived from:

-   -   a. at least 50 mole percent of an aromatic dianhydride based        upon a total dianhydride content of the chemically converted        polyimide; the aromatic dianhydride selected from the group        consisting of: pyromellitic dianhydride, 3,3′,4,4′-biphenyl        tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone        tetracarboxylic dianhydride; 4,4′-oxydiphthalic anhydride,        3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,        2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A        dianhydride, and mixtures thereof;    -   b. at least 50 mole percent of an aromatic diamine based upon a        total diamine content of the chemically converted polyimide; the        aromatic diamine selected from the group consisting of:        3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene,        4,4′-oxydianiline, 1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof;        B. a low conductivity carbon black present in an amount from 2        to 9 weight percent of the base film;        C. a particulate polyimide matting agent present in an amount        from 1.6 to 20 weight percent of the base film, having a density        from 1.3 to 1.5 g/cc, having a median particle size from 1.3 to        10 microns, wherein the particulate polyimide matting agent is        derived from at least 50 mole percent of an aromatic dianhydride        selected from the group consisting of: pyromellitic dianhydride,        3,3′,4,4′-biphenyl tetracarboxylic dianhydride,        3,3′,4,4′-benzophenone tetracarboxylic dianhydride;        4,4′-oxydiphthalic anhydride, 3,3′,4,4′-diphenyl sulfone        tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)        hexafluoropropane, bisphenol A dianhydride, and mixtures        thereof; and at least 50 mole percent of an aromatic diamine        selected from the group consisting of: 3,4′-oxydianiline,        1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,        1,4-diaminobenzene, 1,3-diaminobenzene,        2,2′-bis(trifluoromethyl) benzidene, 4,4′-diaminobiphenyl,        4,4′-diaminodiphenyl sulfide, 9,9′-bis(4-amino)fluorene and        mixtures thereof; wherein the particulate polyimide matting        agent and the chemically converted polyimide have a refractive        index within and including 0.1 unit of each other; and wherein        the base film has a 60 degree gloss value from 2 to 35 on both        sides.

In accordance with any of the above embodiments, the base film is amultilayer film comprising the base film and an adhesive layer.

What is claimed is:
 1. A base film comprising: A. a chemically convertedpolyimide present in an amount from 75 to 96 weight percent of the basefilm, the chemically converted polyimide being derived from: a. at least50 mole percent of an aromatic dianhydride based upon a totaldianhydride content of the chemically converted polyimide; the aromaticdianhydride selected from the group consisting of: pyromelliticdianhydride, 3,3′,4,4′-biphenyl tetracarboxylic dianhydride,3,3′,4,4′-benzophenone tetracarboxylic dianhydride; 4,4′-oxydiphthalicanhydride, 3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A dianhydride,and mixtures thereof; b. at least 50 mole percent of an aromatic diaminebased upon a total diamine content of the chemically convertedpolyimide; the aromatic diamine selected from the group consisting of:3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,1,4-diaminobenzene, 1,3-diaminobenzene, 2,2′-bis(trifluoromethyl)benzidene, 4,4′-diaminobiphenyl, 4,4′-diaminodiphenyl sulfide,9,9′-bis(4-amino)fluorene and mixtures thereof; B. a low conductivitycarbon black present in an amount from 2 to 9 weight percent of the basefilm; and C. a particulate polyimide matting agent present in an amountfrom 1.6 to 9 weight percent of the base film and having a medianparticle size from 1.3 to 10 microns.
 2. The base film in accordancewith claim 1 wherein the particulate polyimide matting agent has arefractive index from 1.65 to 1.85.
 3. The base film in accordance withclaim 1, wherein the particulate polyimide matting agent and thechemically converted polyimide have a refractive index within andincluding 0.1 unit of each other.
 4. The base film in accordance withclaim 1 wherein the particulate polyimide matting agent is derived fromat least 50 mole percent of an aromatic dianhydride and at least 50 molepercent of an aromatic diamine.
 5. A multilayer film comprising the basefilm of claim 1 and an adhesive layer.
 6. The multilayer film inaccordance with claim 5, wherein the adhesive layer is an epoxy resinselected from the group consisting of: bisphenol A type epoxy resin,cresol novolac type epoxy resin, phosphorus containing epoxy resin, andmixtures thereof.
 7. The base film in accordance with claim 1additionally comprising a dye present in an amount from 0.1 to 10 weightpercent.
 8. The base film in accordance with claim 1, wherein the basefilm has a thickness of from 8 to 152 microns.
 9. The base film inaccordance with claim 8, wherein the base film has a thickness of from10 to 40 microns.
 10. A base film comprising: A. a chemically convertedpolyimide present in an amount from 75 to 96 weight percent of the basefilm, the chemically converted polyimide being derived from: a. at least50 mole percent of an aromatic dianhydride based upon a totaldianhydride content of the chemically converted polyimide; the aromaticdianhydride selected from the group consisting of: pyromelliticdianhydride, 3,3′,4,4′-biphenyl tetracarboxylic dianhydride,3,3′,4,4′-benzophenone tetracarboxylic dianhydride; 4,4′-oxydiphthalicanhydride, 3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A dianhydride,and mixtures thereof; b. at least 50 mole percent of an aromatic diaminebased upon a total diamine content of the chemically convertedpolyimide; the aromatic diamine selected from the group consisting of:3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,1,4-diaminobenzene, 1,3-diaminobenzene, 2,2′-bis(trifluoromethyl)benzidene, 4,4′-diaminobiphenyl, 4,4′-diaminodiphenyl sulfide,9,9′-bis(4-amino)fluorene and mixtures thereof; B. a low conductivitycarbon black present in an amount from 2 to 9 weight percent of the basefilm; and C. a particulate polyimide matting agent present in an amountfrom 1.6 to 9 weight percent of the base film, having a median particlesize from 1.3 to 10 microns and having a refractive index from 1.65 to1.85; and wherein the base film has a 60 degree gloss value from 2 to 35on both sides.
 11. The base film in accordance with claim 10, whereinthe base film has a thickness of from 8 to 152 microns.
 12. The basefilm in accordance with claim 11, wherein the base film has a thicknessof from 10 to 40 microns.
 13. A base film comprising: A. a chemicallyconverted polyimide present in an amount from 75 to 96 weight percent ofthe base film, the chemically converted polyimide being derived from: a.at least 50 mole percent of an aromatic dianhydride based upon a totaldianhydride content of the chemically converted polyimide; the aromaticdianhydride selected from the group consisting of: pyromelliticdianhydride, 3,3′,4,4′-biphenyl tetracarboxylic dianhydride,3,3′,4,4′-benzophenone tetracarboxylic dianhydride; 4,4′-oxydiphthalicanhydride, 3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane, bisphenol A dianhydride,and mixtures thereof; b. at least 50 mole percent of an aromatic diaminebased upon a total diamine content of the chemically convertedpolyimide; the aromatic diamine selected from the group consisting of:3,4′-oxydianiline, 1,3-bis-(4-aminophenoxy) benzene, 4,4′-oxydianiline,1,4-diaminobenzene, 1,3-diaminobenzene, 2,2′-bis(trifluoromethyl)benzidene, 4,4′-diaminobiphenyl, 4,4′-diaminodiphenyl sulfide,9,9′-bis(4-amino)fluorene and mixtures thereof; B. a low conductivitycarbon black present in an amount from 2 to 9 weight percent of the basefilm; and C. a particulate polyimide matting agent present in an amountfrom 1.6 to 9 weight percent of the base film and having a medianparticle size from 1.3 to 10 microns, the particulate polyimide mattingagent and the chemically converted polyimide have a refractive indexwithin and including 0.1 unit of each other; and wherein the base filmhas a 60 degree gloss value from 2 to 35 on both sides.
 14. The basefilm in accordance with claim 13, wherein the base film has a thicknessof from 8 to 152 microns.
 15. The base film in accordance with claim 14,wherein the base film has a thickness of from 10 to 40 microns.